1. Field of the Instant Disclosure
The instant disclosure relates to a plug connector, in particular, to an electrical plug capable of preventing inadvertent withdrawal from a socket.
2. Description of Related Art
With the continuous advancement in technology, people are using more electronic devices and information technology (IT) products for personal or work related tasks. These products and devices are manufactured in different sizes and have different functions, however, they share a common characteristic: they are powered through cables or power cords either continuously while in use or in advance. Generally, the cables or power cords are inserted into a socket hole, either at home, in the factory, or in the office through a plug to receive electricity.
The conventional plug includes at least a pair of electrically conductive pins, and the socket has at least two matching holes for fitting the plug. To use the electronic devices, the pins are inserted into the holes to transmit electrical power. However, after the insertion, the plug may loosen or involuntarily detach from the socket due to reasons such as accidental pulling. This possibility may result in poor electrical connection or electrical disconnection.
Please refer to FIG. 6, which shows a schematic view of a plug 2 described in a U.S. patent (U.S. Pat. No. 6,039,591). As shown in FIG. 6, to address the aforementioned issue of inadvertent plug withdrawal, the U.S. Pat. No. 6,039,591 teaches the plug 2 which is engageable to a wall-type socket (not shown). The plug 2 comprises a plug body 28, a swage plate 27, and a shell 26. The plug body 28 includes a base 283, a pair of apertures 281, and a pair of electrically conductive blades 282. The swage plate 27 has a threaded portion 271 and a pair of swages (expanders) 272. The threaded portion 271 is arranged in the shell 26 and engaged to an inner threaded portion 261 of the shell 26. When the shell 26 is rotated by the user, the swage plate 27 is urged forward and rearward with respect to the plug body 28. When the swage plate 27 is impelled forward, the swages 272 are urged into the corresponding blades 282, thereby spreading the blades 282 within the socket. The friction fit provided between the expanded blades 4 and the socket prevents inadvertent plug withdrawal. However, such rotating method may result in the blades being over-tightened to the socket. Furthermore, this type of plug has a much more complicated manufacturing process that incurs a higher production cost.
Referring now to FIG. 7, which shows a schematic view of a safety plug described in another U.S. patent (U.S. Pat. No. 5,082,450). The safety plug comprises a ground prong 37. The ground prong 37 has a top surface 372 that defines an aperture 374. A lock spring 371 and an elongated locking bar 373 are received in the ground prong 37. When the bar 373 is moved to its forward position (shown in FIG. 7), the lock spring 371 is prevented from being deflected downwardly into the ground prong 37. Therefore, when the plug is inserted into the wall-type socket (not shown), the locking bar 373 prevents the ground prong 37 from being inadvertently separated from the socket. However, the lock spring 371 has a complex structure and is not easy to manufacture. The accommodation of the lock spring 371 in the ground prong 37 is also more difficult. When it is desired to disconnect the plug from the socket, the locking bar 373 is retracted to allow the lock spring 371 in returning to its original position. At its original position, the lock spring 371 does not extend upwardly through the aperture 374 in the top surface 372 of the ground prong 37. However, if the lock spring 371 gradually loses its elasticity due to prolonged utilization, the lock spring 371 may be unable to return to its original position due to elastic fatigue. This shortcoming can lead to the malfunction of the plug.
Thus, it is critical to research a simpler, faster, and more efficient method for preventing inadvertent plug withdrawal from the socket. More particularly, an improved method for preventing inadvertent separation of conductive blades from the socket.